A reciprocating internal combustion engine generally comprises an engine block, which includes cylinders, cylinder heads, pistons, connecting rods, a crankshaft and the mainshaft bearings for the crankshaft, and which is inserted in an oiltight manner and with the aid of annular supporting elements insulating against a transmission of structure-borne sound in an outer pan, which consists of two parts connected by screws, wherein the engine block is held at its two ends in the outer pan by means of the supporting elements, which are coaxial to the crankshaft and insulate against a transmission of structure-borne sound, and is sealed to the top edge portion of the outer pan only by an oil seal.
Such internal combustion engine is already known from Laid-open German Application No. 28 01 431. In that known engine the annular supporting elements which insulate against a transmission of structure-borne sound are screw-connected to the engine block and constitute an outer flange, which is screw-connected to the outer pan. In that known engine the large number of fastening screws, which are parallel to the axis of the crankshaft, adds to construction cost, and it has been found that the structural elements which insulate against a transmission of structure-borne noise and which consist, as a rule, of rubber or rubberlike material, are stressed in the direction of the axis of the crankshaft. That stress, which adversely affects the life of said supporting elements, is due to the fact that the axial dimensions of the engine block and of the outer pan do not exactly agree because certain deviations are inevitable in spite of subsequent machining operations. If the supporting elements consist of a rubber-metal connector comprising an inner ring secured to the engine block and an outer ring secured in the outer pan so that the supporting elements will take up also the engine torque, an adhesive joint between the rubber cores of the supporting elements and their outer and inner rings must be provided under the action of heat and the subsequent cooling often results in internal stresses in the supporting elements due to shrinkage. Such stresses have been opposed in that the outer rings were compacted by roll-forming. But such compacting by roll-forming has been hindered by the flanges previously provided on the outer rings. For this reason the flanges are only subsequently formed by a machining operation, which adds to the manufacturing costs. Furthermore the outer pan is assembled from two parts, the parting plane is transverse to the crankshaft and the division serves only to facilitate the installation of the crankshaft.